A wide variety of devices use MEMS switches to selectively transmit current between two points. To that end, MEMS switches often include movable microstructure, such as a cantilevered arm, that is selectively brought into contact with an adjacent conductor. An actuation electrode (or other actuation mechanism) can apply a force, such as an attractive electrostatic force, to the cantilevered arm, urging the arm toward the adjacent conductor. Contact between the arm and the adjacent conductor closes a circuit, permitting current to flow across the switch between the two desired points. Conversely, when the arm and adjacent conductor do not contact, the circuit is open, thus preventing current flow.
The movable microstructure generally must be protected from the environment. If not, then environmental contaminants can severely damage the fragile microstructure, rendering the switch inoperable. Accordingly, MEMS switch microstructure typically is encapsulated within a wafer-level package, such as a cap, to protect the fragile microstructure. Undesirably, caps can increase the risk of a short circuit from the intended closed circuit.